| 摘要 |
954,247. Electron multipliers; electrode materials. BENDIX CORPORATION. Nov. 10, 1961 [Nov. 15, 1960], No. 40373/61. Heading H1D. An electron multiplier comprises at least one magnetic member 20 having a surface 24 with north and south poles along opposite longitudinal sides of it, means for establishing a continuous voltage drop along said surface, another member 22 with a surface 26 facing said first surface, means for establishing another continuous voltage drop along said second surface such that opposite points of both surfaces are at unequal electric potentials to create an electric field whose equipotential lines are oblique to said surfaces, at least one of said surfaces 26 further being secondarily emissive, so that under the joint action of said electric and magnetic fields secondary electrons are accelerated along said secondarily emissive surface. Preferably both members 20, 22 are magnetic with like poles facing each other, composed of rectangular plates of ferrite, and polepieces 34, 36, Fig. 3, may be provided to reduce the reluctance of the magnetic circuit, being separated from the magnets by strips 30, 32 of trifluorochloroethylene. Positive ions or ultra violet radiation incident through a window 40 strike the cathode 28, releasing secondary electrons which follow a cycloidal path 57, increasing in number with each impact with the surface 26, and are finally collected on the anode 42. The secondary emissive material is preferably antimony tin as described in Specification 954,246 and when used to detect ultra violet radiation the cathode 28 is preferably of tungsten, nickel or platinum. |
